A new add-on for Firefox lets you take along one of your most valuable digital assets — your address book — wherever you travel on the social web. The latest experiment to emerge out of Mozilla Labs, Contacts is a Firefox add-on that stores all the contact information for all of your friends on social […]

A new add-on for Firefox lets you take along one of your most valuable digital assets — your address book — wherever you travel on the social web.

The latest experiment to emerge out of Mozilla Labs, Contacts is a Firefox add-on that stores all the contact information for all of your friends on social networks and across multiple address books (both local and web-based) in the browser.

An experimental alpha was first announced in March with the ability to pull in your contacts from Gmail, Twitter and the Mac OS X address book. This week, Contacts received its first update, and can now import data from LinkedIn and Plaxo as well. There are also stability improvements, and some new discovery features that make it easier to find additional information about people who are already in your address book.

In the blog post covering Contacts 0.2, Mozilla’s Michael Hanson says his team is working quickly on adding support for other social networks, Thunderbird’s address book and the Windows address book.

All of us social web junkies have felt the pain involved with “finding friends” on new social networks, or of having to copy and paste e-mail addresses from one place to another just to communicate with somebody on a new web service, or on one we don’t frequently use. Because of this, systems which make your address book, buddy list or other “friend data” accessible across the web are becoming more vital. They essentially give you the ability to sync all of your address books — your own personal Rolodex, that vast store of extremely important data you’ve been cultivating for years, and likely the only social network it’s safe to say you’ll never abandon — and use them on any website you visit.

There are two key components to Contacts. First is an e-mail auto-completion engine, which will auto-complete e-mail addresses on any website you visit without sharing any of your friends’ contact information with the website. Second is an address book API which allows a website to access your own personal contacts database stored in the browser. Of course, you control which sites have permission to access your contacts, and how much of your address book each site can see.

It’s important to note that Mozilla Contacts is still in the early alpha stage, and will become more feature-rich as development continues.

Another interesting component of Mozilla Contacts, introduced in this most recent update, is its discovery engine. There’s a built-in “Person search” tool. If somebody is already in your address book — let’s say you know their name, e-mail address and Twitter handle — you can search the web and collect any publicly available information about them. So if they’ve made their phone number, alternate e-mail address and a list of personal websites available, Contacts will add those things to the person’s record in the database.

Contacts will also automatically discover Webfinger and hCard data about anyone in your address book. The WebFinger integration is especially helpful for anyone who has set up a Google Profile for themselves, because Gmail addresses for people with public Google Profiles are WebFinger-enabled.

All of the data in your Mozilla Contacts is stored using the Portable Contacts format, an emerging standard that promotes interoperability between web-based address books.

These are significant advancements because, as we’ve argued before, identity belongs in the browser. It’s the easiest place for a user to control it, and since the browser is the primary place where users are interacting with services that require authentication or some other identity-centric action (geolocation, web forms) it makes sense to give the browser the power to automate those tasks.

Also, e-mail addresses and URLs are fast becoming a convenient, standard method of identifying one’s self on the social web. OpenID uses the URL model, and think about all of the places you can log in using a Gmail address. Mozilla understands this, and incorporates systems into Contacts that allow you to collect information about somebody by automatically accessing data stored at that person’s various personal URLs and public profile pages. Also, by using Portable Contacts, Mozilla is ensuring it’s as easy as possible for you to get data in and out of Contacts.

In a way, Mozilla has been leading up to something like Contacts for years, beginning with its Weave project for syncing bookmarks, history and other personal data across multiple instances of Firefox, and more recently with the Raindrop web server. Weave and Contacts compliment each other nicely. We wouldn’t be surprised to see them become integrated in the future.